1. Field of the Invention
The invention relates to a projection system, more particularly to a light valve device suitable for a projection system.
2. Description of the Related Art
Since the projection image quality of a projection system is directly affected by a light valve in the projection system, it is extremely important to maintain a suitable operating temperature of the light valve. With reference to FIG. 1 and FIG. 2, a conventional light valve device 1 includes a light valve 11 disposed on a supporting seat 12, which is disposed on a first side of a circuit board 13. A heat-dissipating structure 14 is disposed on a second side of the circuit board 13 opposite to the first side. The heat-dissipating structure 14 includes a heat-dissipating main body 141 and a heat-dissipating block 142. The heat-dissipating main body 141 includes a plurality of heat-dissipating fins 143. A heat-dissipating sheet 15 interconnects the heat-dissipating block 142 and the light valve 11. Heat generated by the light valve 11 is transferred into the air via the heat-dissipating block 142 and the heat-dissipating main body 141, thereby cooling the light valve 11.
The heat-dissipating structure 14 is normally made of aluminum, which is relatively lightweight. However, since the operating temperature of the light valve 11 becomes increasingly higher as demand for luminance in images projected by the projection system increases, aluminum is being replaced with copper or other materials having better heat conductivity so as to improve the heat-dissipating capability of the heat-dissipating structure 14. However, since copper is more costly and is heavier than aluminum, a common practice is to only make the heat-dissipating block 142 be made of copper, while the heat-dissipating main body 141 is still made of aluminum.
However, when the heat-dissipating main body 141 and the heat-dissipating block 142 are made of different materials, engagement therebetween becomes difficult. Two engaging methods for the heat-dissipating main body 141 and the heat-dissipating block 142 are used at present. One engaging method involves soldering the heat-dissipating block 142 to the heat-dissipating main body 141. However, the cost of soldering is high, and the durability of the heat-dissipating structure 14 decreases. The second engaging method involves locking the heat-dissipating block 142 to the heat-dissipating main body 141 via screw fasteners (not shown). However, not only do screw fasteners degrade the heat-dissipating capability of the heat-dissipating structure 14, but formation of screw holes and screw threads and locking of the screw fasteners also increase the manufacturing cost of the conventional light valve device 1. Moreover, since loosening of the screw fasteners is difficult to detect, the stability of the heat-dissipating structure 14 is adversely affected.